body {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh; /* 设置最小高度为 100% 的视口高度 */
    background-color: #eee;
    background-image: url('/img/bg.jpg'); /* 替换为你的背景图片路径 */
    background-size: cover;
    background-repeat: no-repeat;
    background-position: center;
}

.form-signin {
    max-width: 450px;
    padding: 15px;
    margin: 0 auto;
    background: rgba(255, 255, 255, 0.8); /* 半透明背景 */
    border-radius: 10px;
}

.form-signin .form-signin-heading,
.form-signin .checkbox {
    margin-bottom: 10px;
}

.form-signin .checkbox {
    font-weight: normal;
}

/* 居中标题和描述 */
.form-signin-heading {
    text-align: center;
    margin-bottom: 20px;
}

.form-signin .form-control {
    position: relative;
    height: auto;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    padding: 10px;
    font-size: 16px;
    margin-bottom: 10px; /* 增加input之间的空隙 */
}

.form-signin .form-control:focus {
    z-index: 2;
}

.form-signin input[type="text"],
.form-signin input[type="password"],
.form-signin select {
    margin-bottom: 10px;
    border-radius: 5px;
}

.form-signin button {
    margin-bottom: 10px;
    font-size: 16px;
}

.form-signin .btn-primary {
    background-color: #337ab7;
}

.form-signin .btn-register {
    background-color: #5cb85c;
    border-color: #4cae4c;
}

#errorMessage {
    display: none;
    color: red;
    font-size: 14px;
}

.form-group {
    display: flex;
    align-items: center; /* 垂直居中对齐 */
}

/* 可以根据需要调整水平间距 */
.form-group img {
    margin-right: 10px; /* 为了增加验证码图片和输入框之间的间距 */
}